This invention relates to a photosensitive member for electrophotography, more particularly comprising a specified nylon copolymer.
There is known a conventional photosensitive member for electrophotography constituted of a surface protective layer and a photoconductive layer on an electrically conductive substrate in the order.
The surface protective layer functions to prevent the photoconductive layer from being deteriorated by abrasion in a cleaning process, ozone (O.sub.3), or nitrogen oxides (NO.sub.x) which are produced by corona discharge.
For example, Japanese Patent Laid-open No. 57-204559 discloses a photosensitive member for electrophotography in which a surface protective layer prepared with a polyester amide-containing insulating resin is formed on a photoconductive layer. The polyester amide contained in the surface protective layer is a copolymer of an ester unit represented by the chemical formula (I) or (II) below with an amide unit represented by the chemical formula (III) or (IV) below: The copolymerization ratio (ester unit /amide unit) is 20/80-85/15. ##STR1##
There is also known a surface protective layer formed of ceramics such as Al.sub.2 O.sub.3, ZrO.sub.2, amorphous carbon and the like or metallic materials in consideration of wearing resistance with respect to durability, stability for electrostatic properties or the like.
Polyester amide used for the formation of the surface protective layer as above mentioned is made soluble in a solvent by controlling its crystallinity. However, its solubility is not sufficient from the view point of workability for coating. The ester component causes the lack in humidity resistance and wearing resistance, resulting in copied image flows and wear of the surface protective layer. Moreover, the surface protective layer containing the ester components has high electrical resistance to cause the accumulation of residual potential, resulting in the formation of fogs and nonuniform copied images.
The surface protective layer formed of ceramics or metallic materials is poor in its adhesivity to a photoconductive layer, resulting in the generation of cracks in the surface protective layer. Therefore, it does not exhibit sufficient durability with respect to the copy.